Hammerhead TCP Coil Support Radial Offset for RF Arcing

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Solution Overview

Problem

In plasma etching processes, arcing between screws supporting the TCP coil in plasma processing chambers occurs due to high voltage potential differences, leading to damage such as charring, flaking, or breakage of the ceramic support, especially at higher RF power levels.

Innovation Solution

A ceramic support with a hammerhead shape and non-threaded screws is used to radially offset screw placements, reducing the likelihood of arcing by creating a non-continuous ring around the outer coil and minimizing electric field concentration through smooth shank screws and elongated passages for terminal supports.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If fully threaded screws are used to support the TCP coil, then the structural strength and fixation capability are improved, but the electric field concentration increases leading to arcing and ceramic support damage

Engineering Contradiction:

Improvestructural strengthVSAvoidarcing and electric field concentration

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

The screw structure is segmented into two distinct parts: a threaded section for securing the TCP coil and a smooth shank section that passes through the ceramic support. This segmentation allows the threaded portion to provide fixation strength while the smooth portion eliminates electric field concentration and prevents arcing at the ceramic-screw interface.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The harmful threaded section is extracted from the portion of the screw that contacts the ceramic support. By removing the threads from the ceramic-contacting section and using only a smooth shank, the invention eliminates the source of electric field concentration and arcing while maintaining structural integrity through the threaded section that engages with the TCP coil.

Inventive Principle:

Principle #2Taking out (Extraction)

2Ease of operation

If screws are placed closer together to provide better support, then the fixation capability is improved, but the likelihood of arcing between screws increases

Engineering Contradiction:

Improvefixation capabilityVSAvoidarcing resistance

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The smooth shank section acts as an intermediary between the threaded fixation section and the ceramic support. This smooth intermediate section prevents electric field concentration and arcing, allowing screws to be placed closer together for better fixation without compromising reliability, as the smooth shank eliminates the arcing hazard between closely spaced screws.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Productivity

If higher RF power levels are used to improve processing efficiency, then the productivity is improved, but the arcing and damage to ceramic support increases

Engineering Contradiction:

Improveprocessing efficiencyVSAvoidarcing and ceramic damage

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The invention converts the potentially harmful effect of high RF power by eliminating the arcing mechanism through smooth shank screws. By removing the threaded sections that concentrate electric fields, the system can operate at higher RF power levels for improved productivity without suffering from arcing-induced ceramic damage, thus turning the high power condition from a harmful scenario into a beneficial one.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The solution significantly reduces arcing and associated damage to the ceramic support, allowing for higher RF power operation without damage, with a reduction in electric field concentration and arcing incidents by up to 30% compared to fully threaded screws.

Implementation Method 1

minimizing electric field concentration through smooth shank screws

Methodology Applied

Scientific EffectElectric field concentration: Electric Field

Implementation Method 2

reducing the likelihood of arcing by creating a non-continuous ring around the outer coil

Methodology Applied

Scientific EffectArcing: Electric Arc

Data Source

PatentUS9384948B2Hammerhead TCP coil support for high RF power conductor etch systems

Publication Date: 2016.07.05 LAM RES CORP

AI summary

The chamber, having a ceramic window disposed in a ceiling of the chamber is provided. Included is a ceramic support having a plurality of spokes that extend from a center region to an outer periphery, and each of the spokes include a hammerhead shape that radially expands the ceramic support in a direction that is away from an axis of a spoke. Also included is a plurality of screw holes disposed through the ceramic support. The plurality of screw holes defined to enable screws to connect to a TCP coil having an inner and outer coil. The outer coil is to be disposed under the hammerhead shape of each of the spokes, and a radial gap is defined between each of the hammerhead shapes. The radial gap defines a non-continuous ring around the outer coil. A plurality of screws are disposed through the screw holes for attaching the TCP coil.